Large industrial washers are commonly used in the healthcare, pharmaceutical, and scientific research industries. The washers are used to remove contaminants and biological waste from large objects, such as racks of animal cages, and healthcare and scientific equipment, such as hospital beds, wheelchairs, medical instruments, utensils, carts, instrument containers, and the like. The washer includes a washing chamber with a large opening for providing access to the washing chamber. A door seals the opening, and opens to allow a load to be located inside the washing chamber. The washing chamber may be over six feet tall and several feet wide and deep to accommodate the aforementioned items.
Since the fluids used within such washing chambers are often heated, significant fluctuations in pressure can occur within the washing chamber during a washing cycle. More specifically, considerable differences in temperature in liquids and gases (e.g., air) used during a washing cycle or during an exhaust or drying cycle, can produce either an increased pressure in the washing chamber as compared to the surrounding environment (i.e., a positive pressure), or a vacuum in the washing chamber as compared to the surrounding environment (i.e., a negative pressure). Moreover, in the event of a vacuum condition within the washing chamber, it is important that “unfiltered air” not be drawn into the chamber, as this would allow contaminants to enter the washing chamber, and thus impair the effectiveness of the washer.
The present invention provides a pressure equalization system that prevents large fluctuations in pressure in a washing chamber.